"If you have interest rates where they are then you will prop up all asset classes. So it's a little expensive for my taste," he said Tuesday at the Delivering Alpha conference sponsored by CNBC and Institutional Investor.

The Federal Reserve has held interest rates low for a decade, and only in December hiked from near-zero levels. Speculation has mounted whether the U.S. central bank will boost the federal funds rate at its meeting later this month.

Schwarzman said Fed policymakers may act soon, joking they could raise rates just because they are "bored."

"They'll probably start later this year," he said, adding that a hike will "move markets."

What he's been buying

Schwarzman said Blackstone bought some assets this year after periods of dislocation. He said the firm purchased United Kingdom real estate after its vote to leave the European Union.

He added that Blackstone bought some "beaten-down" Brazilian assets and also sees some opportunities in United States real estate.